diff --git a/www/js/controllers.js b/www/js/controllers.js
index 4819b91..acbc0ad 100644
--- a/www/js/controllers.js
+++ b/www/js/controllers.js
@@ -36,7 +36,7 @@ MIM.controller('ConfigController', function ($ionicPlatform, $ionicLoading, $loc
   });
 });
 
-MIM.controller('SalesController', function ($scope, $ionicPlatform, $cordovaSQLite, $ionicPopup, Customer) {
+MIM.controller('SalesController', function ($scope, $ionicPopup, Customer, Product, Sale) {
   $scope.customers = [];
   $scope.products = [];
 
@@ -44,57 +44,29 @@ MIM.controller('SalesController', function ($scope, $ionicPlatform, $cordovaSQLi
     $scope.customers = customers;
   });
 
-  var productQuery = 'SELECT id, name FROM Products WHERE remaining_amount > 0';
-  $cordovaSQLite.execute(db, productQuery, []).then(function (res) {
-    if (res.rows.length) {
-      for (var i = 0; i < res.rows.length; i++) {
-        $scope.products.push({
-          id: res.rows.item(i).id,
-          product_name: res.rows.item(i).name,
-        });
-      }
-    }
-  }, function (error) {
-    console.error(error);
+  Product.hasAmount().then(function (products) {
+    $scope.products = products;
   });
 
-  $scope.addSale = function (saleData) {
-    var transactQuery = 'INSERT INTO Transactions (categories, total_price, ' +
-      'status, customer_id) VALUES (?, ?, ?, ?)';
-    var buyQuery = 'INSERT INTO Buying (transaction_id, product_id, amount) VALUES (?, ?, ?)';
-    $cordovaSQLite.execute(db, transactQuery, ["P", saleData.total_price, "1", saleData.customers]).then(function (tx) {
-      $cordovaSQLite.execute(db, buyQuery, [tx.insertId, saleData.products, saleData.amount]).then(function (res) {
-        console.log('Customer id ' + saleData.customers + ' and Transaction id ' +
-          tx.insertId + ' are successfully inserted.');
-        $scope.getRemainingAmount(saleData.products, saleData.amount);
-        $scope.updateProductAmount(saleData.products, saleData.amount);
-        $scope.showAlert();
-        saleData.newItem = '';
-      }, function (error) {
-        console.error(error);
-      });
+  $scope.addSale = function(saleData) {
+    Sale.addTransaction(saleData).then(function (res) {
+      Sale.addBuying(res.insertId, saleData);
+      $scope.getRemainingAmount(saleData.products, saleData.amount);
+      $scope.updateProductAmount(saleData.products, saleData.amount);
+      $scope.showAlert();
+      saleData.newItem = '';
     });
   };
 
-  $scope.getRemainingAmount = function (id, amount) {
-    var query = 'SELECT remaining_amount FROM Products WHERE id = ?';
-    $cordovaSQLite.execute(db, query, [id]).then(function (res) {
-      if (res.rows.length) {
-        $scope.remaining_amount = res.rows.item(0).remaining_amount - amount;
-        $scope.updateProductAmount(id, $scope.remaining_amount);
-      }
-    }, function (error) {
-      console.error(error);
+  $scope.getRemainingAmount = function(id, amount) {
+    Product.getAmount(id).then(function (productAmount) {
+      $scope.remaining_amount = productAmount.remaining_amount - amount;
+      $scope.updateProductAmount(id, $scope.remaining_amount);
     });
   };
 
-  $scope.updateProductAmount = function (id, remaining_amount) {
-    var query = 'UPDATE Products SET remaining_amount = ? WHERE id = ?';
-    $cordovaSQLite.execute(db, query, [remaining_amount, id]).then(function (res) {
-      console.log('one row is affected');
-    }, function (error) {
-      console.error(error);
-    });
+  $scope.updateProductAmount = function(id, remaining_amount) {
+    Product.updateAmount(id, remaining_amount);
   };
 
   $scope.showAlert = function () {
@@ -102,13 +74,14 @@ MIM.controller('SalesController', function ($scope, $ionicPlatform, $cordovaSQLi
       title: 'Success',
       template: 'A new transaction has been added',
     });
+
     alertPopup.then(function (res) {
       console.log('Transaction is successfully added.');
     });
   };
 });
 
-MIM.controller('SalesOrderController', function ($scope, $ionicPlatform, $cordovaSQLite, $ionicModal, $ionicPopup, Customer, Product) {
+MIM.controller('SalesOrderController', function ($scope, $ionicModal, $ionicPopup, Customer, Product, Order) {
   $scope.customers = [];
   $scope.products = [];
   $scope.orders = [];
@@ -121,43 +94,26 @@ MIM.controller('SalesOrderController', function ($scope, $ionicPlatform, $cordov
     $scope.products = products;
   });
 
-    var query = 'SELECT t.id AS id, c.name AS name FROM Transactions t, Customers c ' +
-      'WHERE categories = ? AND t.customer_id = c.id';
-    $cordovaSQLite.execute(db, query, ["O"]).then(function (res) {
-      if (res.rows.length) {
-        for (var i = 0; i < res.rows.length; i++) {
-          $scope.orders.push({
-            id: res.rows.item(i).id,
-            customer_name: res.rows.item(i).name,
-          });
-        }
-      }
-    }, function (error) {
-      console.error(error);
+  $scope.$on('$ionicView.enter', function () {
+    $scope.populateOrders();
+  });
+
+  $scope.populateOrders = function () {
+    Order.all('O').then(function (orders) {
+      $scope.orders = orders;
     });
+  };
 
-  $scope.addOrder = function (ordersData) {
-    var transactQuery = 'INSERT INTO Transactions (categories, total_price, ' +
-      'status, customer_id) VALUES (?, ?, ?, ?)';
-    var orderQuery = 'INSERT INTO Buying (transaction_id, product_id, amount) VALUES (?, ?, ?)';
-    var query = 'SELECT name FROM Customers WHERE id = ?';
-    $cordovaSQLite.execute(db, transactQuery, ["O", ordersData.total_price, "0", ordersData.customers]).then(function (tx) {
-      $cordovaSQLite.execute(db, orderQuery, [tx.insertId, ordersData.products, ordersData.amount]).then(function (res) {
-        $cordovaSQLite.execute(db, query, [ordersData.customers]).then(function (res) {
-          if (res.rows.length) {
-            $scope.orders.push({
-              id: tx.insertId,
-              customer_name: res.rows.item(0).name,
-            });
-            ordersData.newItem = '';
-            $scope.closeOrderModal();
-            console.log('Customer id ' + ordersData.customers + ' and ' +
-              'Transaction id ' + tx.insertId + ' are successfully inserted.');
-          }
-        }, function (error) {
-          console.error(error);
-        });
+  $scope.addOrder = function(ordersData) {
+    Order.addTransaction(ordersData).then(function (res) {
+      Order.addOrder(res.insertId, ordersData);
+      Customer.get(ordersData.customers).then(function (customers) {
+        console.log('Customer id ' + ordersData.customers + ' and ' +
+          'Transaction id ' + res.insertId + ' are successfully inserted.');
       });
+      $scope.populateOrders();
+      $scope.closeOrderModal();
+      ordersData.newItem = '';
     });
   };
 
@@ -185,17 +141,12 @@ MIM.controller('SalesOrderController', function ($scope, $ionicPlatform, $cordov
       title: 'Delete an Order',
       template: 'Are you sure you want to delete this sale order?',
     });
+
     confirmPopup.then(function (res) {
       if (res) {
-        var outerQuery = 'DELETE FROM Buying WHERE transaction_id = ?';
-        var innerQuery = 'DELETE FROM Transactions WHERE id = ?';
-        $cordovaSQLite.execute(db, outerQuery, [order.id]).then(function (tx) {
-          $cordovaSQLite.execute(db, innerQuery, [order.id]).then(function (tx) {
-            $scope.orders.splice($scope.orders.indexOf(order), 1);
-          });
-        }, function (error) {
-          console.error(error);
-        });
+        Order.deleteBuying(order.id);
+        Order.deleteTransaction(order.id);
+        $scope.populateOrders();
       } else {
         console.log('You cancel deleting this sale order.');
       }
@@ -203,34 +154,19 @@ MIM.controller('SalesOrderController', function ($scope, $ionicPlatform, $cordov
   };
 });
 
-MIM.controller('OrderDetailController', function ($scope, $ionicPlatform, $cordovaSQLite, $stateParams) {
-  $ionicPlatform.ready(function () {
-    var query = 'SELECT p.name AS name, b.amount AS amount, t.total_price ' +
-      'AS total_price FROM Transactions t, Buying b, Products p WHERE ' +
-      't.id = b.transaction_id AND b.product_id = p.id AND t.id = ?';
-    $cordovaSQLite.execute(db, query, [$stateParams.orderId]).then(function (res) {
-      if (res.rows.length) {
-          $scope.product_name = res.rows.item(0).name;
-          $scope.order_amount = res.rows.item(0).amount;
-          $scope.order_price = res.rows.item(0).total_price;
-      }
-    }, function (error) {
-      console.error(error);
-    });
+MIM.controller('OrderDetailController', function ($scope, $stateParams, Order) {
+  Order.get($stateParams.orderId).then(function (orderDetail) {
+    $scope.product_name = orderDetail.name;
+    $scope.order_amount = orderDetail.amount;
+    $scope.order_price = orderDetail.total_price;
   });
 });
 
-MIM.controller('AddInventoryController', function ($scope, $cordovaSQLite, $ionicPopup) {
-  $scope.addProduct = function (productData) {
-    var query = 'INSERT INTO Products (name, description, remaining_amount, ' +
-      'selling_price, purchase_price) VALUES (?, ?, ?, ?, ?)';
-    $cordovaSQLite.execute(db, query, [productData.name, productData.description, productData.amount, productData.selling_price, productData.purchase_price]).then(function (res) {
-      console.log('Item ' + res.insertId + ' is successfully inserted.');
-      $scope.showAlert();
-      productData.newItem = '';
-    }, function (error) {
-      console.error(error);
-    });
+MIM.controller('AddInventoryController', function ($scope, $ionicPopup, Product) {
+  $scope.addProduct = function(productData) {
+    Product.add(productData);
+    $scope.showAlert();
+    productData.newItem = '';
   };
 
   $scope.showAlert = function () {
@@ -238,43 +174,33 @@ MIM.controller('AddInventoryController', function ($scope, $cordovaSQLite, $ioni
       title: 'Success',
       template: 'A new item has been added',
     });
+
     alertPopup.then(function (res) {
       console.log('Item is successfully inserted.');
     });
   };
 });
 
-MIM.controller('InventoryItemsController', function ($scope, $ionicPlatform, $cordovaSQLite, $ionicModal, $ionicPopup) {
+MIM.controller('InventoryItemsController', function ($scope, $ionicModal, $ionicPopup, Product) {
   $scope.inventory = [];
-  $ionicPlatform.ready(function () {
-    var query = 'SELECT id, name, remaining_amount FROM Products ORDER BY remaining_amount DESC';
-    $cordovaSQLite.execute(db, query, []).then(function (res) {
-      if (res.rows.length) {
-        for (var i = 0; i < res.rows.length; i++) {
-          $scope.inventory.push({
-            id: res.rows.item(i).id,
-            product_name: res.rows.item(i).name,
-            product_amount: res.rows.item(i).remaining_amount,
-          });
-        }
-      }
-    }, function (error) {
-      console.error(error);
-    });
+
+  $scope.$on('$ionicView.enter', function () {
+    $scope.populateProducts();
   });
 
-  $scope.editItem = function (productData) {
-    var query = 'UPDATE Products SET name = ?, description = ?, ' +
-      'selling_price = ?, purchase_price = ?, updated_at = DATETIME(\'now\') WHERE id = ?';
-    $cordovaSQLite.execute(db, query, [productData.name, productData.description, productData.selling_price, productData.purchase_price, productData.id]).then(function (res) {
-      console.log('Item ' + productData.id + ' is updated.');
-      productData.newItem = '';
-      $scope.closeItemModal();
-    }, function (error) {
-      console.error(error);
+  $scope.populateProducts = function () {
+    Product.orderByAmount().then(function (products) {
+      $scope.inventory = products;
     });
   };
 
+  $scope.editItem = function(productData) {
+    Product.update(productData);
+    $scope.populateProducts();
+    $scope.closeItemModal();
+    $scope.cleanForm();
+  };
+
   $ionicModal.fromTemplateUrl('templates/edit_item.html', {
     scope: $scope,
     animation: 'slide-in-up',
@@ -284,20 +210,16 @@ MIM.controller('InventoryItemsController', function ($scope, $ionicPlatform, $co
 
   $scope.openItemModal = function (item) {
     $scope.productData = {};
-    var query = 'SELECT id, name, description, remaining_amount, selling_price, ' +
-      'purchase_price FROM Products WHERE id = ?';
-    $cordovaSQLite.execute(db, query, [item.id]).then(function (res) {
-      if (res.rows.length) {
-        $scope.productData.id = res.rows.item(0).id;
-        $scope.productData.name = res.rows.item(0).name;
-        $scope.productData.description = res.rows.item(0).description;
-        $scope.productData.amount = res.rows.item(0).remaining_amount;
-        $scope.productData.purchase_price = res.rows.item(0).purchase_price;
-        $scope.productData.selling_price = res.rows.item(0).selling_price;
-      }
-    }, function (error) {
-      console.error(error);
+
+    Product.get(item.id).then(function (itemData) {
+      $scope.productData.id = itemData.id;
+      $scope.productData.name = itemData.name;
+      $scope.productData.description = itemData.description;
+      $scope.productData.amount = itemData.remaining_amount;
+      $scope.productData.purchase_price = itemData.purchase_price;
+      $scope.productData.selling_price = itemData.selling_price;
     });
+
     $scope.modal.show();
   };
 
@@ -305,6 +227,10 @@ MIM.controller('InventoryItemsController', function ($scope, $ionicPlatform, $co
     $scope.modal.hide();
   };
 
+  $scope.cleanForm = function () {
+    productData.newItem = '';
+  };
+
   $scope.$on('$destroy', function () {
     $scope.modal.remove();
   });
@@ -314,14 +240,11 @@ MIM.controller('InventoryItemsController', function ($scope, $ionicPlatform, $co
       title: 'Delete an Item',
       template: 'Are you sure you want to delete this item?',
     });
+
     confirmPopup.then(function (res) {
       if (res) {
-        var query = 'DELETE FROM Products WHERE id = ?';
-        $cordovaSQLite.execute(db, query, [item.id]).then(function (tx) {
-          $scope.inventory.splice($scope.inventory.indexOf(item), 1);
-        }, function (error) {
-          console.error(error);
-        });
+        Product.delete(item);
+        $scope.populateProducts();
       } else {
         console.log('You cancel deleting this item.');
       }
@@ -329,61 +252,43 @@ MIM.controller('InventoryItemsController', function ($scope, $ionicPlatform, $co
   };
 });
 
-MIM.controller('ItemDetailController', function ($scope, $ionicPlatform, $cordovaSQLite, $stateParams) {
-  $ionicPlatform.ready(function () {
-    var query = 'SELECT name, description, remaining_amount, selling_price, ' +
-      'purchase_price, DATETIME(created_at, \'localtime\') AS created_date, ' +
-      'DATETIME(updated_at, \'localtime\') AS updated_date ' +
-      'FROM Products WHERE id = ?';
-    $cordovaSQLite.execute(db, query, [$stateParams.itemId]).then(function (res) {
-      if (res.rows.length) {
-        $scope.product_name = res.rows.item(0).name;
-        $scope.product_description = res.rows.item(0).description;
-        $scope.product_amount = res.rows.item(0).remaining_amount;
-        $scope.purchase_price = res.rows.item(0).selling_price;
-        $scope.selling_price = res.rows.item(0).purchase_price;
-        $scope.created_date = res.rows.item(0).created_date;
-        $scope.updated_date = res.rows.item(0).updated_date;
-      }
-    }, function (error) {
-      console.error(error);
-    });
+MIM.controller('ItemDetailController', function ($scope, $stateParams, Product) {
+  Product.get($stateParams.itemId).then(function (itemDetail) {
+    $scope.product_name = itemDetail.name;
+    $scope.product_description = itemDetail.description;
+    $scope.product_amount = itemDetail.remaining_amount;
+    $scope.purchase_price = itemDetail.selling_price;
+    $scope.selling_price = itemDetail.purchase_price;
+    $scope.created_date = itemDetail.created_date;
+    $scope.updated_date = itemDetail.updated_date;
   });
 });
 
-MIM.controller('CustomerController', function ($scope, $ionicPlatform, $cordovaSQLite, $ionicModal, $ionicPopup, Customer) {
+MIM.controller('CustomerController', function ($scope, $ionicModal, $ionicPopup, Customer) {
   $scope.customers = [];
 
-  Customer.all().then(function (customers) {
-    $scope.customers = customers;
+  $scope.$on('$ionicView.enter', function () {
+    $scope.populateCustomers();
   });
 
-  $scope.addCustomer = function (customersData) {
-    var query = 'INSERT INTO Customers (name, address, telephone_number) VALUES (?, ?, ?)';
-    $cordovaSQLite.execute(db, query, [customersData.name, customersData.address, customersData.phone]).then(function (res) {
-      $scope.customers.push({
-        id: res.insertId,
-        customer_name: customersData.name,
-        customer_address: customersData.address,
-        customer_phone: customersData.phone,
-      });
-      customersData.newItem = '';
-      $scope.closeCustomerModal(1);
-    }, function (error) {
-      console.error(error);
+  $scope.populateCustomers = function () {
+    Customer.all().then(function(customers) {
+      $scope.customers = customers;
     });
   };
 
-  $scope.editCustomer = function (customersData) {
-    var query = 'UPDATE Customers SET name = ?, address = ?, telephone_number = ?, ' +
-      'updated_at = DATETIME(\'now\') WHERE id = ?';
-    $cordovaSQLite.execute(db, query, [customersData.name, customersData.address, customersData.phone, customersData.id]).then(function (res) {
-      console.log('Item ' + customersData.id + ' is updated.');
-      customersData.newItem = '';
-      $scope.closeCustomerModal(2);
-    }, function (error) {
-      console.error(error);
-    });
+  $scope.addCustomer = function(customersData) {
+    Customer.add(customersData);
+    $scope.populateCustomers();
+    $scope.closeCustomerModal(1);
+    $scope.cleanForm();
+  };
+
+  $scope.editCustomer = function(customersData) {
+    Customer.update(customersData);
+    $scope.populateCustomers();
+    $scope.closeCustomerModal(2);
+    $scope.cleanForm();
   };
 
   $ionicModal.fromTemplateUrl('templates/add_customer.html', {
@@ -426,6 +331,10 @@ MIM.controller('CustomerController', function ($scope, $ionicPlatform, $cordovaS
     }
   };
 
+  $scope.cleanForm = function () {
+    customersData.newItem = '';
+  };
+
   $scope.$on('$destroy', function () {
     $scope.addModal.remove();
     $scope.editModal.remove();
@@ -436,14 +345,11 @@ MIM.controller('CustomerController', function ($scope, $ionicPlatform, $cordovaS
       title: 'Delete Customer',
       template: 'Are you sure you want to delete this customer?',
     });
+
     confirmPopup.then(function (res) {
       if (res) {
-        var query = 'DELETE FROM Customers WHERE id = ?';
-        $cordovaSQLite.execute(db, query, [customer.id]).then(function (tx) {
-          $scope.customers.splice($scope.customers.indexOf(customer), 1);
-        }, function (error) {
-          console.error(error);
-        });
+        Customer.delete(customer);
+        $scope.populateCustomers();
       } else {
         console.log('You cancel deleting this customer.');
       }
@@ -461,41 +367,35 @@ MIM.controller('CustomerDetailController', function ($scope, $stateParams, Custo
   });
 });
 
-MIM.controller('StatisticsController', function ($scope, $ionicPlatform, $cordovaSQLite) {
+MIM.controller('StatisticsController', function ($scope, Statistic) {
   $scope.month_year = [];
   $scope.monthly_transaction = [];
   $scope.monthly_income = [];
   $scope.series = ["month-year"];
   $scope.count = [];
   $scope.total_price = [];
-  $ionicPlatform.ready(function () {
-    var transactionQuery = 'SELECT strftime(\'%m-%Y\', date) AS month_year, COUNT(id) AS total_transaction ' +
-      'FROM Transactions GROUP BY month_year';
-    $cordovaSQLite.execute(db, transactionQuery, []).then(function (res) {
-      if (res.rows.length) {
-        for (var i = 0; i < res.rows.length; i++) {
-          $scope.month_year.push(res.rows.item(i).month_year);
-          $scope.count.push(res.rows.item(i).total_transaction);
-        }
-      }
-    }, function (error) {
-      console.error(error);
-    });
 
+  $scope.$on('$ionicView.enter', function () {
+    $scope.drawTransactionStat();
     $scope.monthly_transaction.push($scope.count);
+    $scope.drawIncomeStat();
+    $scope.monthly_income.push($scope.total_price);
+  });
 
-    var incomeQuery = 'SELECT strftime(\'%m-%Y\', date) AS month_year, SUM(total_price) AS total_price ' +
-      'FROM Transactions GROUP BY month_year';
-      $cordovaSQLite.execute(db, incomeQuery, []).then(function (res) {
-        if (res.rows.length) {
-          for (var i = 0; i < res.rows.length; i++) {
-            $scope.total_price.push(res.rows.item(i).total_price);
-          }
-        }
-      }, function (error) {
-        console.error(error);
-      });
+  $scope.drawTransactionStat = function () {
+    Statistic.getTransaction().then(function (res) {
+      for (var i = 0; i < res.length; i++) {
+        $scope.month_year.push(res[i].month_year);
+        $scope.count.push(res[i].total_transaction);
+      }
+    });
+  };
 
-      $scope.monthly_income.push($scope.total_price);
-  });
+  $scope.drawIncomeStat = function () {
+    Statistic.getIncome().then(function (res) {
+      for (var i = 0; i < res.length; i++) {
+        $scope.total_price.push(res[i].total_price);
+      }
+    });
+  };
 });
diff --git a/www/js/services.js b/www/js/services.js
index 6729c21..b6b53c2 100644
--- a/www/js/services.js
+++ b/www/js/services.js
@@ -59,6 +59,23 @@ MIM.factory('Customer', function ($cordovaSQLite, DB) {
     });
   };
 
+  this.add = function(customer) {
+    var parameters = [customer.name, customer.address, customer.phone];
+    return DB.queryStatement("INSERT INTO Customers (name, address, telephone_number) " +
+      "VALUES (?, ?, ?)", parameters);
+  };
+
+  this.update = function (customer) {
+    var parameters = [customer.name, customer.address, customer.phone, customer.id];
+    return DB.queryStatement('UPDATE Customers SET name = ?, address = ?, telephone_number = ?, ' +
+      'updated_at = DATETIME(\'now\') WHERE id = ?', parameters);
+  };
+
+  this.delete = function (customer) {
+    var parameters = [customer.id];
+    return DB.queryStatement('DELETE FROM Customers WHERE id = ?', parameters);
+  };
+
   return this;
 });
 
@@ -69,5 +86,168 @@ MIM.factory('Product', function ($cordovaSQLite, DB) {
     });
   };
 
+  this.hasAmount = function () {
+    return DB.queryStatement('SELECT id, name FROM Products WHERE remaining_amount > 0').then(function (res) {
+      return DB.getAll(res);
+    });
+  };
+
+  this.get = function (productId) {
+    var parameters = [productId];
+    return DB.queryStatement('SELECT id, name, description, remaining_amount, ' +
+      'selling_price, purchase_price, DATETIME(created_at, \'localtime\') AS ' +
+      'created_date, DATETIME(updated_at, \'localtime\') AS updated_date ' +
+      'FROM Products WHERE id = ?', parameters).then(function (res) {
+      return DB.getById(res);
+    });
+  };
+
+  this.getAmount = function (productId) {
+    var parameters = [productId];
+    return DB.queryStatement('SELECT remaining_amount FROM Products WHERE id = ?', parameters).then(function (res) {
+      return DB.getById(res);
+    });
+  };
+
+  this.add = function (product) {
+    var parameters = [
+      product.name,
+      product.description,
+      product.amount,
+      product.selling_price,
+      product.purchase_price,
+    ];
+    return DB.queryStatement('INSERT INTO Products (name, description, remaining_amount, ' +
+      'selling_price, purchase_price) VALUES (?, ?, ?, ?, ?)', parameters);
+  };
+
+  this.update = function (product) {
+    var parameters = [
+      product.name,
+      product.description,
+      product.selling_price,
+      product.purchase_price, product.id,
+    ];
+    return DB.queryStatement('UPDATE Products SET name = ?, description = ?, ' +
+      'selling_price = ?, purchase_price = ?, updated_at = DATETIME(\'now\') ' +
+      'WHERE id = ?', parameters);
+  };
+
+  this.updateAmount = function (productId, productAmount) {
+    var parameters = [productAmount, productId];
+    return DB.queryStatement('UPDATE Products SET remaining_amount = ? WHERE id = ?', parameters);
+  };
+
+  this.delete = function (product) {
+    var parameters = [product.id];
+    return DB.queryStatement('DELETE FROM Products WHERE id = ?', parameters);
+  };
+
+  this.orderByAmount = function () {
+    return DB.queryStatement('SELECT id, name, remaining_amount FROM Products ' +
+      'ORDER BY remaining_amount DESC').then(function (res) {
+      return DB.getAll(res);
+    });
+  };
+
+  return this;
+});
+
+MIM.factory('Order', function ($cordovaSQLite, DB) {
+  this.all = function (orderCategory) {
+    var parameters = [orderCategory];
+    return DB.queryStatement('SELECT t.id AS id, c.name AS name FROM Transactions t, ' +
+      'Customers c WHERE categories = ? AND t.customer_id = c.id', parameters)
+      .then(function (res) {
+        return DB.getAll(res);
+    });
+  };
+
+  this.get = function (orderId) {
+    var parameters = [orderId];
+    return DB.queryStatement('SELECT p.name AS name, b.amount AS amount, ' +
+      't.total_price AS total_price FROM Transactions t, Buying b, Products p ' +
+      'WHERE t.id = b.transaction_id AND b.product_id = p.id AND t.id = ?', parameters)
+      .then(function (res) {
+        return DB.getById(res);
+    });
+  };
+
+  this.addTransaction = function (ordersData) {
+    var parameters = [
+      'O',
+      ordersData.total_price,
+      '0',
+      ordersData.customers,
+    ];
+    return DB.queryStatement('INSERT INTO Transactions (categories, total_price, ' +
+      'status, customer_id) VALUES (?, ?, ?, ?)', parameters);
+  };
+
+  this.addOrder = function (transactionId, ordersData) {
+    var parameters = [
+      transactionId,
+      ordersData.products,
+      ordersData.amount,
+    ];
+    return DB.queryStatement('INSERT INTO Buying (transaction_id, product_id, ' +
+      'amount) VALUES (?, ?, ?)', parameters);
+  };
+
+  this.deleteBuying = function (orderId) {
+    var parameters = [orderId];
+    return DB.queryStatement('DELETE FROM Buying WHERE transaction_id = ?', parameters);
+  };
+
+  this.deleteTransaction = function (orderId) {
+    var parameters = [orderId];
+    return DB.queryStatement('DELETE FROM Transactions WHERE id = ?', parameters);
+  };
+
+  return this;
+});
+
+MIM.factory('Sale', function ($cordovaSQLite, DB) {
+  this.addTransaction = function (saleData) {
+    var parameters = [
+      'P',
+      saleData.total_price,
+      '1',
+      saleData.customers,
+    ];
+    return DB.queryStatement('INSERT INTO Transactions (categories, total_price, ' +
+      'status, customer_id) VALUES (?, ?, ?, ?)', parameters);
+  };
+
+  this.addBuying = function (transactionId, saleData) {
+    var parameters = [
+      transactionId,
+      saleData.products,
+      saleData.amount,
+    ];
+    return DB.queryStatement('INSERT INTO Buying (transaction_id, product_id, ' +
+      'amount) VALUES (?, ?, ?)', parameters);
+  };
+
+  return this;
+});
+
+MIM.factory('Statistic', function ($cordovaSQLite, DB) {
+  this.getTransaction = function () {
+    return DB.queryStatement('SELECT strftime(\'%m-%Y\', date) AS month_year, ' +
+      'COUNT(id) AS total_transaction FROM Transactions GROUP BY month_year')
+      .then(function (res) {
+        return DB.getAll(res);
+    });
+  };
+
+  this.getIncome = function () {
+    return DB.queryStatement('SELECT strftime(\'%m-%Y\', date) AS month_year, ' +
+      'SUM (total_price) AS total_price FROM Transactions GROUP BY month_year')
+      .then(function (res) {
+        return DB.getAll(res);
+    });
+  };
+
   return this;
 });
diff --git a/www/templates/inventory_items.html b/www/templates/inventory_items.html
index 05337c8..aeffefd 100644
--- a/www/templates/inventory_items.html
+++ b/www/templates/inventory_items.html
@@ -2,8 +2,8 @@
   <ion-content>
     <ion-list>
       <ion-item ng-repeat="item in inventory" href="#/app/item-detail/{{ item.id }}">
-        {{ item.product_name }}
-        <span class="badge badge-balanced">{{ item.product_amount }}</span>
+        {{ item.name }}
+        <span class="badge badge-balanced">{{ item.remaining_amount }}</span>
         <ion-option-button class="button-positive icon ion-android-create" ng-click="openItemModal(item)"></ion-option-button>
         <ion-option-button class="button-assertive icon ion-android-delete" ng-click="deleteItem(item)"></ion-option-button>
       </ion-item>
diff --git a/www/templates/sales.html b/www/templates/sales.html
index 79c2e28..7456b3b 100644
--- a/www/templates/sales.html
+++ b/www/templates/sales.html
@@ -10,7 +10,7 @@
         </label>
         <label class="item item-input item-select">
           <span class="input-label">Product Name</span>
-          <select name="products" ng-model="saleData.products" ng-options="product.id as product.product_name for product in products" required>
+          <select name="products" ng-model="saleData.products" ng-options="product.id as product.name for product in products" required>
             <option value="">Choose item</option>
           </select>
         </label>
diff --git a/www/templates/sales_order.html b/www/templates/sales_order.html
index f9150a0..95c5803 100644
--- a/www/templates/sales_order.html
+++ b/www/templates/sales_order.html
@@ -5,7 +5,7 @@
   <ion-content>
     <ion-list>
       <ion-item ng-repeat="order in orders" href="#/app/order-detail/{{ order.id }}">
-        {{ order.customer_name }}
+        {{ order.name }}
         <ion-option-button class="button-assertive icon ion-android-delete" ng-click="deleteOrder(order)"></ion-option-button>
       </ion-item>
       <ion-item ng-show="!orders.length">No order :(</ion-item>